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Examples: Configuring CoS for Aggregated Ethernet and SONET/SDH Interfaces

Configure queues as follows when the total speed of member link interfaces is 100 Mbps (the available bandwidth is 100 Mbps):

Apply Scaling Formula to Absolute Rates



[edit class-of-service]
schedulers {


be {
transmit-rate 10m;
}




af {
transmit-rate 20m;
}




ef {
transmit-rate 80m;
}




nc {
transmit-rate 30m;
}


}

The total configured transmit rates of the aggregated interface is 10m + 20m + 80m + 30m = 140 Mbps, meaning the transmit rate is overconfigured by 40 percent. Therefore, the software scales down the configuration to match the 100 Mbps of available bandwidth, as follows:



be = (10/140) * 100 = 7 percent of 100 Mbps = 7 Mbps
af = (20/140) * 100 = 14 percent of 100 Mbps = 14 Mbps
ef = (80/140) * 100 = 57 percent of 100 Mbps = 57 Mbps
nc = (30/140) * 100 = 21 percent of 100 Mbps = 21 Mbps

Configure the following mixture of percent and absolute rates:

Apply Scaling Formula to Mixture of Percent and Absolute Rates



[edit class-of-service]
schedulers {


be {
transmit-rate 20 percent;
}




af {
transmit-rate 40 percent;
}




ef {
transmit-rate 150m;
}




nc {
transmit-rate 10 percent;
}


}

Assuming 300 Mbps of available bandwidth, the configured percentages correlate with the following absolute rates:



schedulers {


be {
transmit-rate 60m;
}




af {
transmit-rate 120m;
}




ef {
transmit-rate 150m;
}




nc {
transmit-rate 30m;
}


}

The software scales the bandwidth allocation as follows:



be = (60/360) * 100 = 17 percent of 300 Mbps = 51 Mbps
af = (120/360) * 100 = 33 percent of 300 Mbps = 99 Mbps
ef = (150/360) * 100 = 42 percent of 300 Mbps = 126 Mbps
nc = (30/360) * 100 = 8 percent of 300 Mbps = 24 Mbps

Configure an aggregated Ethernet interface with the following scheduler map:

Configuring an Aggregated Ethernet Interface



[edit class-of-service]
scheduler-maps {


aggregated-sched {
forwarding-class be scheduler be;
forwarding-class af scheduler af;
forwarding-class ef scheduler ef;
forwarding-class nc scheduler nc;
}


}
schedulers {


be {
transmit-rate percent 10;
buffer-size percent 25;
}




af {
transmit-rate percent 20;
buffer-size percent 25;
}




ef {
transmit-rate 80m;
buffer-size percent 25;
}




nc {
transmit-rate percent 30;
buffer-size percent 25;
}


}

In this case, the transmission rate for the member link scheduler map is as follows:

be—7 percent
af—14 percent
ef—57 percent
nc—21 percent

If you add a Fast Ethernet interface to the aggregate, the aggregate bandwidth is 200 Mbps, and the transmission rate for the member link scheduler map is as follows:

be—10 percent
af—20 percent
ef—40 percent
nc—30 percent

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